Flutter of Very Flexible Swept Pazy Wings

The study investigates the aeroelastic behavior of very flexible, sweptback wings derived from the straight Pazy wing, through computational analyses. Using the Pazy wing as a benchmark, the study evaluates how large deformations and varying sweep angles affect the natural frequencies, mode shapes, flutter characteristics, and static aeroelastic response. The modal rotation method and Nastran software are used to conduct static aeroelastic and flutter analyses under various subsonic air speeds and low to moderate angles of attack. Findings show that flutter in very flexible swept wings is governed by two independent effects: sweep angle and bending deformation. Wing sweep has a stabilizing effect on the hump flutter mode while bending results in a decrease of flutter onset speed, which is almost independent of the sweep angle. Static aeroelastic analyses indicate that the strip-theory aerodynamic model, which assumes undeformed lift-line slopes, may not be adequate for accurate swept-wing deformation predictions. The study highlights the need for nonlinear structural modeling and adequate aerodynamic modeling in flexible swept wings, and it suggests further experimental validation.